linux-kernel - Re: [PATCH v3] net: vmw_vsock: vmci: Check memcpy_from

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Message-ID: <C39CC4BC-E87C-4C6D-ADC9-A33E7696BD20@vmware.com>
Date:   Mon, 5 Dec 2022 23:03:47 +0000
From:   Vishnu Dasa <vdasa@...are.com>
To:     Artem Chernyshev <artem.chernyshev@...-soft.ru>
CC:     Stefano Garzarella <sgarzare@...hat.com>,
        Pv-drivers <Pv-drivers@...are.com>,
        Bryan Tan <bryantan@...are.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linux Virtualization <virtualization@...ts.linux-foundation.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "lvc-project@...uxtesting.org" <lvc-project@...uxtesting.org>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v3] net: vmw_vsock: vmci: Check memcpy_from_msg()


> On Dec 5, 2022, at 3:52 AM, Artem Chernyshev <artem.chernyshev@...-soft.ru> wrote:
> 
> vmci_transport_dgram_enqueue() does not check the return value
> of memcpy_from_msg(). Return with an error if the memcpy fails.

I think we can add some more information in the description.  Sorry, I
should've said this earlier.

vmci_transport_dgram_enqueue() does not check the return value
of memcpy_from_msg().  If memcpy_from_msg() fails, it is possible that
uninitialized memory contents are sent unintentionally instead of user's
message in the datagram to the destination.  Return with an error if
memcpy_from_msg() fails.

> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 0f7db23a07af ("vmci_transport: switch ->enqeue_dgram, ->enqueue_stream and ->dequeue_stream to msghdr")
> Signed-off-by: Artem Chernyshev <artem.chernyshev@...-soft.ru>

Thanks, Artem!  This version looks good to me modulo my suggestion
about the description above.

Reviewed-by: Vishnu Dasa <vdasa@...are.com>

Regards,
Vishnu

> ---
> V1->V2 Fix memory leaking and updates for description
> V2->V3 Return the value of memcpy_from_msg()
> 
> net/vmw_vsock/vmci_transport.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
> index 842c94286d31..36eb16a40745 100644
> --- a/net/vmw_vsock/vmci_transport.c
> +++ b/net/vmw_vsock/vmci_transport.c
> @@ -1711,7 +1711,11 @@ static int vmci_transport_dgram_enqueue(
> 	if (!dg)
> 		return -ENOMEM;
> 
> -	memcpy_from_msg(VMCI_DG_PAYLOAD(dg), msg, len);
> +	err = memcpy_from_msg(VMCI_DG_PAYLOAD(dg), msg, len);
> +	if (err) {
> +		kfree(dg);
> +		return err;
> +	}
> 
> 	dg->dst = vmci_make_handle(remote_addr->svm_cid,
> 				   remote_addr->svm_port);
> -- 
> 2.30.3
>